(i) Differences between repetitive DNA and satellite DNA are:
Repetitive DNA :
It is the non-coding DNA with multiple copies of identical sequences, which may lie in , tandem or interspersed.
These can be few base pairs to hundreds or thousands of base pairs long.
In CsCl density gradient analysis, They appear as light bands.
Satellite DNA :
Refers to non-coding tandem repeating sequences.
These are generally short sequence repeats (upto 60 base pair long).
These appear as small dark bands.

(ii) Differences between mRNA and tRNA are:

mRNA
It is called messenger RNA and carries the codes for amino acid sequence.
It is a long chain of bases with large molecular weight (25-200000 Dalton).
It is synthesised by RNA polymerase II.
tRNA :
It is called transfer RNA as it carries amino acids to the site of protein synthesis.
It is a clover-leaf like structure, with small molecular weight (25000 Dalton).
Synthesised by RNA polymerase III.